1. Field of Invention
The present invention is directed generally to image-guided medical procedures, and more particularly, to systems and methods for the storage and geometric measurement of instrument trajectories used in image-based surgical guided navigation systems.
2. Description of the Related Art
Image based surgical techniques have been used with success in aiding physicians for performing a wide variety of delicate surgical procedures. These procedures are typically used when the visualization of a surgical tool could be obscured by a patient's anatomy, or when the surgical tool is visible but the patient's anatomy may be difficult to visualize in three dimensions. Such procedures include, for example, spinal implant placement, the alignment of broken bone fragments, and the fixation of bone fractures. Prior art techniques to accurately position a surgical instrument have included the use of x-ray images to localize its position. Through the repeated acquisition of x-ray images during the procedure, real-time placement of the instrument relative to the patient's anatomy can be displayed. More recently, virtual fluoroscopically-based surgical navigation systems have been employed to track an instrument trajectory and superimpose its representation onto pre-acquired images without requiring x-rays to be repeatedly taken during the actual surgical procedure.
In many situations, a surgeon would like to create a static visual reference using the real-time and generally instantaneous instrument trajectory displayed by the surgical navigation system as the instrument progresses in the general direction of a selected, desired path. For example, some procedures require the serial placement of several implants which must be placed in a precise relative geometry. Currently, the surgeon must reacquire a new set of images after each implant is placed to properly determine the trajectory of the subsequent implant. This can be a time consuming process which increases the amount of radiation exposure to the patient and operating room personnel.
Other situations may require the surgeon to make accurate geometric measurements of a patient's anatomy. For example, some surgical procedures require the precise removal of a specific amount of bone taken in the shape of a wedge. In order to determine this amount, an angular measurement of the bone at the surgical site would assist in this procedure. Another example would be in allowing the surgeon to make distance measurement between bone implant sites to ensure proper implant placement. In light of the foregoing, there is a need for the ability to save surgical instrument trajectories and have the capability to perform measurements thereon.